As is well known, the set of rolls in a supercalender comprises a number of rolls, which have been arranged one above the other as a stack of rolls. The rolls placed one above the other are in nip contact with each other, and the paper web to be calendered is arranged to pass through the nips between the rolls. Supercalenders involve the drawback that in supercalenders the nips are loaded by the force of the weight of the set of rolls, in which case the distribution of the linear load from the upper nip to the lower nip is increasing in a substantially linear way. This has the consequence that the linear load present in the lower nip determines the loading capacity of the calender. Thus, the calender is dimensioned in compliance with the performance of the lowest rolls and, at the same time, some of the loading or calendering potential of the upper nips remains unused. Earlier, attempts have been made to solve this drawback related to the prior art so that attempts have been made to increase the deficient loading of the upper nips so that the supercalender is placed in the horizontal plane or that the stack of rolls in the calender is divided into two stacks of rolls. Such an embodiment has, however, also proved expensive, because a calender of two parts requires a higher number of adjustable-crown rolls. One embodiment in which the set of rolls in the calender has been divided into two stacks of rolls is described in the DE Utility Model Application No. 295 04 034.3. In this prior-art solution, in the calender divided in two stacks of rolls, the paper web is first passed through the calendering nips in one stack of rolls, and after that the paper web is passed into the other stack of rolls, in which the paper web is passed through its calendering nips.
In the way known from the prior art, in supercalenders, first one side, for example the top side, of the paper web has been calendered/glazed, and then the other side, for example the bottom side. In the prior-art solutions, a so-called reversing nip has determined where the side to be glazed is changed. In supercalenders, the glazing takes place most intensively in the first nips, in which case the glazing of the side that is glazed in the later nips to the same glaze level as is reached by the side glazed first requires, relatively speaking, higher linear loads, and this causes a higher loss of bulk in the web. Also, the difficult control of successive glazing often produces unequalsidedness in the paper glaze degree.